Transmutation of MAs and LLFPs with a lead-cooled fast reactor

The management of nuclear wastes has long been a problem that hinders the sustainable and clean utilization of nuclear energy since the advent of nuclear power. These nuclear wastes include minor actinides (MAs: ²³⁷Np, ²⁴¹Am, ²⁴³Am, ²⁴⁴Cm and ²⁴⁵Cm) and long-lived fission products (LLFPs: ⁷⁹Se, ⁹³Zr, ⁹⁹Tc, ¹⁰⁷Pd, ¹²⁹I and ¹³⁵Cs), and yet are hard to be handled. In this work, we propose a scheme that can transmute almost all the MAs and LLFPs with a lead-cooled fast reactor (LFR). In this scheme, the MAs and the LLFPs are loaded to the fuel assembly and the blanket assembly for transmutation, respectively. In order to study the effect of MAs loading on the operation of the core, the neutron flux distribution, spectra, and the k_eff are further compared with and without MAs loading. Then the LLFPs composition is optimized and the support ratio is obtained to be 1.22 for ²³⁷Np, 1.63 for ²⁴¹Am, 1.27 for ²⁴³Am, 1.32 for ⁷⁹Se, 1.53 for ⁹⁹Tc, 1.02 for ¹⁰⁷Pd, and 1.12 for ¹²⁹I, respectively, indicating that a self-sustained transmutation can be achieved. Accordingly, the transmutation rate of these nuclides was 13.07%/y for ²³⁷Np, 15.18%/y for ²⁴¹Am, 13.34%/y for ²⁴³Am, 0.58%/y for ⁷⁹Se, 0.92%/y for ⁹⁹Tc, 1.17%/y for ¹⁰⁷Pd, 0.56%/y for ¹²⁹I. Our results show that a lead-cooled fast reactor can be potentially used to manage nuclear wastes with high levels of long-lived radioactivity.

[Blood-borne occupation exposures in dental practice of medical staff: status and protection]

Objective: To understand the status of blood-borne occupational exposure and protection among health care workers (HCWs) in dental practice, and provide evidence for making effective prevention. Methods: From April 1 to 15, 2019, a stratified random sampling method was conducted to investigate the data of blood-borne occupational exposure among 221 dental HCWs in 2018, and Chi-squared Test was used to evaluate the differences of status on occupational exposure and protection among different professionals, such as nurses, doctors and trainees, and among different-grade hospitals. Results: A total of 166 HCWs were exposed to occupational exposure 269 times, with the annual incidence of 75.11% (166/221) , and 37.55% (101/269) of exposures were reported. However, all source patients of exposures had failed to be traced. 89.59% (241/269) of exposures were sharp injuries. The top three instruments caused injuries were syringe/bilan needles, suture needles and vehicle needles, accounting for 35.68% (86/241) 、16.60% (40/241) and 16.18% (39/241) , respectively; and the top three exposure operations were removal/disposal of needles or instruments, suture/assisting suture and injection of anesthetic, accounting for 37.17% (100/269) 、22.30% (60/269) and 17.84% (48/269) , respectively. There were statistically significant differences among different professionals in occupational exposure frequency, reporting rate, the types of instruments caused injuries, exposure operations and hepatitis B vaccinated time (P<0.01) . The compliance rate of standard precautions, safe operation, post-exposure reporting and prevention, and training on occupational protection were generally poor among HCWs, with significant differences in different-grade hospitals (P<0.01) . Conclusion: There is a high incidence, low reporting rate and poor self-protection of blood-borne occupational exposure among dental HCWs. Strongly suggesting that standard precautions, safe use and disposal of oral instruments, active post-exposure report and prevention must be improved for everyone.

Cruciferous vegetables intake and the risk of colorectal cancer: a meta-analysis of observational studies

BACKGROUND

Epidemiological studies have reported inconsistent associations between cruciferous vegetable (CV) intake and colorectal cancer (CRC) risk. To our knowledge, a comprehensive and quantitative assessment of the association between CV intake and CRC has not been reported.

METHODS

Relevant articles were identified by searching MEDLINE. We pooled the relative risks (RR) from individual studies using a random-effect model and carried out heterogeneity and publication bias analyses.

RESULTS

Twenty-four case-control and 11 prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (RR: 0.82; 95% confidence interval 0.75-0.90) intake and CRC risk. Specific analysis for cabbage and broccoli yielded similar result. When separately analyzed, case-control studies of CV intake yield similar results, and the results from the prospective studies showed borderline statistical significance. Moreover, significant inverse associations were also observed in colon cancer and its distal subsite both among prospective and case-control studies.

CONCLUSIONS

Findings from this meta-analysis provide evidence that high intake of CV was inversely associated with the risk of CRC and colon cancer in humans. Further analysis on other specific CV, food preparation methods, stratified results by anatomic cancer site, and subsite of colon cancer should be extended in future study.

Mutations in the beta-myosin heavy chain gene in southern Chinese families with hypertrophic cardiomyopathy

In this study, 14 unrelated hypertrophic cardiomyopathy (HCM) probands were scanned by polymerase chain reaction-single-strand conformation polymorphism analysis and DNA sequencing. Three mis-sense mutations of the beta-myosin heavy chain gene, MYH7, were found: valine (Val) 606 methionine (Met), arginine (Arg) 694 leucine (Leu), and Arg 723 glycine (Gly). All are reported here for the first time in Chinese subjects. The results showed that: Val606Met is an intermediate malignancy mutation; Arg694Leu is a novel mutation with a benign phenotype; and the Arg723Gly mutation is linked to malignancy - it can lead not only to HCM but also to dilated cardiomyopathy at various ages. The clinical symptoms associated with Arg723Gly emerged early and caused more severe clinical manifestation and poorer prognosis in females than in males. Mis-sense mutations were not detected in the myosin binding protein C, cardiac, cardiac troponin T type 2, or cardiac troponin I type 3 genes. The MYH7 gene may be an HCM mutation hotspot in the Chinese and have unique features in this study population.

BIGEL analysis of gene expression in HL60 cells exposed to X rays or 60 Hz magnetic fields

We screened a panel of 1,920 randomly selected cDNAs to discover genes that are differentially expressed in HL60 cells exposed to 60 Hz magnetic fields (2 mT) or X rays (5 Gy) compared to unexposed cells. Identification of these clones was accomplished using our two-gel cDNA library screening method (BIGEL). Eighteen cDNAs differentially expressed in X-irradiated compared to control HL60 cells were recovered from a panel of 1,920 clones. Differential expression in experimental compared to control cells was confirmed independently by Northern blotting of paired total RNA samples hybridized to each of the 18 clone-specific cDNA probes. DNA sequencing revealed that 15 of the 18 cDNA clones produced matches with the database for genes related to cell growth, protein synthesis, energy metabolism, oxidative stress or apoptosis (including MYC, neuroleukin, copper zinc-dependent superoxide dismutase, TC4 RAS-like protein, peptide elongation factor 1alpha, BNIP3, GATA3, NF45, cytochrome c oxidase II and triosephosphate isomerase mRNAs). In contrast, BIGEL analysis of the same 1,920 cDNAs revealed no differences greater than 1.5-fold in expression levels in magnetic-field compared to sham-exposed cells. Magnetic-field-exposed and control samples were analyzed further for the presence of mRNA encoding X-ray-responsive genes by hybridization of the 18 specific cDNA probes to RNA from exposed and control HL60 cells. Our results suggest that differential gene expression is induced in approximately 1% of a random pool of cDNAs by ionizing radiation but not by 60 Hz magnetic fields under the present experimental conditions.

Csa-19, a radiation-responsive human gene, identified by an unbiased two-gel cDNA library screening method in human cancer cells

A novel polymerase chain reaction (PCR)-based method was used to identify candidate genes whose expression is altered in cancer cells by ionizing radiation. Transcriptional induction of randomly selected genes in control versus irradiated human HL60 cells was compared. Among several complementary DNA (cDNA) clones recovered by this approach, one cDNA clone (CL68-5) was downregulated in X-irradiated HL60 cells but unaffected by 12-O-tetradecanoyl phorbol-13-acetate, forskolin, or cyclosporin-A. DNA sequencing of the CL68-5 cDNA revealed 100% nucleotide sequence homology to the reported human Csa-19 gene. Northern blot analysis of RNA from control and irradiated cells revealed the expression of a single 0.7-kilobase (kb) messenger RNA (mRNA) transcript. This 0.7-kb Csa-19 mRNA transcript was also expressed in a variety of human adult and corresponding fetal normal tissues. Moreover, when the effect of X- or fission neutron-irradiation on Csa-19 mRNA was compared in cultured human cells differing in p53 gene status (p53-/- versus p53+/+), downregulation of Csa-19 by X-rays or fission neutrons was similar in p53-wild type and p53-null cell lines. Our results provide the first known example of a radiation-responsive gene in human cancer cells whose expression is not associated with p53, adenylate cyclase or protein kinase C.

Rodent cell transformation and immediate early gene expression following 60-Hz magnetic field exposure

Some epidemiological studies suggest that exposure to power frequency magnetic fields (MFs) may be associated with an elevated risk of human cancer, but the experimental database remains limited and controversial. We investigated the hypothesis that 60-Hz MF action at the cellular level produces changes in gene expression that can result in neoplastic transformation. Twenty-four hour 200 microT continuous MF exposure produced negative results in two standard transformation systems (Syrian hamster embryo cells and C3H/10T1/2 murine fibroblasts) with or without postexposure to a chemical promoter. This prompted a reexamination of previously reported MF-induced changes in gene expression in human HL60 cells. Extensive testing using both coded and uncoded analyses was negative for an MF effect. Using the same exposure conditions as in the transformation studies, no MF-induced changes in ornithine decarboxylase expression were observed in C3H/10T1/2 cells, casting doubt on a promotional role of MF for the tested cells and experimental conditions.

Effects of Different Cooking Methods on the Yield of Carotenoids in Water Convolvulus ( Ipomoea aquatica )

The effect of microwave, steam, and conventional cooking treatments on the yield of carotenoids in water convolvulus was studied. Each cooking treatment was conducted for 0, 2, 4, 8, and 16 min with two replications. A slight modification of AOAC method was used to determine carotene and xanthophyll content. The mean carotene and xanthophyll contents in fresh raw samples were significantly higher than those of all the cooked samples. Xanthophyll concentrations had greater loss than carotene during cooking. Conventional cooking had lower carotene and xanthophyll content than either microwave or steam cooking. The highest and lowest yields of carotenoids, 86 and 53%, were found in steam and conventional cooking with the heating time 2 and 16 min, respectively.

Menstrual blood loss and hematologic indices in healthy Chinese women

Menstrual blood loss, cyanmethemoglobin and serum ferritin were determined in 421 healthy, noncontracepting Chinese women. The range of menstrual blood loss (MBL) was 4.1-273.6 mL, the mean value was 54.2 mL, and the median was 42.9 mL. The range of hemoglobin was 8.3-16.7 g/dL, and the mean value was 13.2 g/dL. The range of ferritin was 1.2-180.0 ng/mL, the mean value was 22.8 ng/mL, and the geometric mean was 17.1 ng/mL. The upper normal limit of MBL in Chinese women was set at 80 mL.

Menstrual blood loss, haemoglobin and ferritin concentration of Beijing women wearing steel ring, VCu 200, and TCu 220c IUDs

Menstrual blood loss (MBL), serum ferritin and whole blood cyanmethemoglobin were measured at pre- and 1, 3, 6, 12, 18 and 24th postinsertion cycles in 60 women wearing the Steel Ring, the Copper V (VCu 200) or the Copper T (TCu 220c). The MBL, incidence of menorrhagia and iron deficiency anemia were lower among users of the Steel Ring than among users of the Copper V and T. Anemia occurred later and the duration of menstruation was shorter with the Steel Ring than with the Copper T. There were no statistically significant differences between the Copper V and T.

A randomized comparative clinical evaluation of the Steel Ring, the VCu200 and the TCu220c IUDs

A randomized comparative clinical study of the Steel Ring, VCu200 and TCu220c IUDs was carried out in Beijing. Six-hundred subjects were recruited and each group of 200 was inserted with one of the three devices. The TCu220c and the VCu200 had statistically significantly lower pregnancy and expulsion rates at one and two years of use than the Steel Ring. However, the Steel Ring consistently had the lowest rate of removal for pain and/or bleeding. At two years, the early differences of use-related discontinuation and continuation between the higher rates of the Steel Ring and the lower rates of the VCu200 and TCu220c were significantly reduced. There were no statistically significant differences of net event rates between VCu200 and TCu220c.